How Sea Level Rise and Tidal Flooding Threaten U.S. East and Gulf Coast Communities over the Next 30 Years

The analysis warns that sea level rise will cause tidal flooding to become chronic and widespread across the U.S. East and Gulf Coasts by 2045. Many communities will see a tripling or more of annual flood events, with some locations facing over 180 floods per year. The report emphasizes the need for urgent local and national adaptation strategies, including infrastructure upgrades and emissions reductions, to manage the inevitable disruptions to daily life and infrastructure.

• By 2030, more than half of the 52 analyzed communities on the East and Gulf Coasts are projected to average over 24 tidal floods annually, with two-thirds potentially experiencing a tripling or more of their current annual flood frequency.
• By 2045, one-third of the analyzed locations are expected to face tidal flooding more than 180 times per year on average, and nine specific locations, including Cape May and Atlantic City, NJ, could see 240 or more annual events.
• The mid-Atlantic coast is projected to experience some of the most significant increases in flood frequency, with cities like Washington, DC, and Annapolis, MD, potentially averaging over 150 tidal floods annually by 2030.
• Tidal flooding will expand into areas currently unaffected; for example, New London, CT, could increase from two annual floods today to over 35 by 2045, while Gulf Coast locations like Freeport, Rockport, and Sabine Pass, TX, could face 35 to 70 floods per year by 2045.
• Higher sea levels will allow high tides to push water further inland and create longer-lasting flood conditions, meaning extensive flooding that previously required storms may occur from tides alone in places like Savannah, GA, and Lewisetta, VA, within one or two decades.
• The report argues that coastal adaptation has fundamental limits; in some areas, structural defenses will be impossible or too costly, eventually requiring communities to shift back from the shore.

APA

Union of Concerned Scientists (2014). How Sea Level Rise and Tidal Flooding Threaten U.S. East and Gulf Coast Communities over the Next 30 Years. https://www.ucs.org/sites/default/files/attach/2014/10/encroaching-tides-executive-summary.pdf

Chicago

Union of Concerned Scientists. How Sea Level Rise and Tidal Flooding Threaten U.S. East and Gulf Coast Communities over the Next 30 Years. 2014. https://www.ucs.org/sites/default/files/attach/2014/10/encroaching-tides-executive-summary.pdf.

Wikipedia

{{cite report |author=Union of Concerned Scientists |title=How Sea Level Rise and Tidal Flooding Threaten U.S. East and Gulf Coast Communities over the Next 30 Years |date=October 2014 |url=https://www.ucs.org/sites/default/files/attach/2014/10/encroaching-tides-executive-summary.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{unionofconcernedscientists2014how, author = {{Union of Concerned Scientists}}, title = {{How Sea Level Rise and Tidal Flooding Threaten U.S. East and Gulf Coast Communities over the Next 30 Years}}, institution = {Union of Concerned Scientists}, year = {2014}, month = oct, url = {https://www.ucs.org/sites/default/files/attach/2014/10/encroaching-tides-executive-summary.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }